Gravekeeper's Supernaturalist

As an additional cost to cast this spell, sacrifice two Gravekeeper creatures. Gravekeeper's Supernaturalist gets +X/+X where X is the combined mana value of the sacrificed creatures.

At the beginning of your end phase, you may search your library for a Gravekeeper creature or a "Necrovalley" card, add it to your hand then shuffle your library.